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Caltrans Releases Climate Change Vulnerability Assessments

Caltrans has released two Climate Change Vulnerability Assessments as part of an effort to understand how and where climate change may impact the State Highway System. The new reports for Northern California and the Central Valley continue the department’s efforts to assess all regions of the state. The assessments evaluate risks, including extreme temperatures, increased precipitation, storm surge, wildfire risk and sea level rise.

These Climate Change Vulnerability Assessments identify specific locations along the State Highway System heavily impacted by frequent wildfires in recent years. In the northeast corner of the state, assessments were conducted within the counties of Shasta, Tehama, Plumas, Lassen, Modoc, Trinity and Siskiyou, and within California’s Central Valley and Sierra Nevada counties assessments were conducted in Madera, Fresno, Tulare, Kings and Kern counties.

By identifying the possible risks and implications of climate change, the reports seek to guide future planning processes and investments to ensure the long-term future of California’s transportation system.

“Climate change is an immediate and escalating threat to California and its transportation system, and Caltrans is being proactive,” said Caltrans Director Laurie Berman. “We are looking at where the state highway system is vulnerable, so we can address issues moving forward.”

Extreme weather and its associated costs are expected to become more pronounced and more frequent in the future as a result of climate change. Events are tied together, as a wildfire can scorch crucial vegetation on hillsides that would otherwise help soak-up storm runoff in the winter. This can lead to flooding and severe erosion of state roadways.

The Summary Reports for the two new assessments provide an overview of the extent and locations of possible climate impacts. The more in-depth Technical Reports provide technical information and the methods of analysis used to determine the potential exposure of these State Highway Systems. These assessments will be followed with a study of the appropriate responses.

The reports are supported by an extensive GIS database and Caltrans has developed an interactive mapping application for public use, which shows impacted locations and the climate model results.

The reports and the interactive mapping application can be accessed at:

Using data from the studies, Caltrans intends to help evaluate the vulnerability of other modes of transportation through partnerships and data sharing with local and regional agencies. As Caltrans moves toward a resilient transportation system, the department will continue to enhance its climate change efforts and partnerships with local, regional, state and federal agencies in order to create coordinated adaptation solutions for the state transportation system.

Caltrans has been considering the impact of climatic changes on the state transportation system and developed guidance and studies on how climate change can be incorporated into planning and project design. This also aligns with Governor Edmund G. Brown Jr.’s call to integrate climate change into transportation investment decisions.

Caltrans’ first Climate Change Vulnerability Assessment was for the Bay Area region and was released in late 2017. This assessment highlighted the impact of the severe storm season of winter 2016-2017 in California, which caused severe flooding, landslides and coastal erosion totaling over $1.2 billion in highway damages statewide. Nearly $390 million of those damages occurred in the Bay Area.

Caltrans’ current policy and guidance documents can be found at